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Seasonic M12-II 520w Bronze Review

We were fortunate enough to have been given a chance by Seasonic to review their M12-II 520w Bronze psu. This unit is basically an upgraded M12-D that promises 80+ Bronze levels of efficiency (the psu name already implies this!) coupled with an excellent value-for-money proposition.

Lets see if this unit is perfect for the average Juan or Pedro who is looking to upgrade his rig for long hours of intense gaming.

Before we Begin

This review is limited in many respects. As such, we have decided to make one that an average tech fan at home can try using equipment that is easily available to him. Here are some of the limitations:

» Testing has been limited to voltage fluctuation resulting from the introduction of load while subjecting the test unit to air intake temperatures that are typical of a home computer; i.e. 40 degrees celcius. The local distro had been kind enough to lend us a hotbox just for this purpose!

» Efficiency testing was not carried out with the provided wattmeter because we believed that the readings obtained by Hardware Secrets using their professional equipment were far more accurate. We were forced to test the psu using a test rig with only a load of 299w because nobody wanted to lend us a monster video card.

» We couldn’t afford to make a resistive load tester mainly because we can’t afford one and that the average Juan or Pedro doesn’t have the know-how to make one in the first place.

» Except for the purpose-built hotbox and Omni wattmeter that Seasonic’s distro lent us, the testing equipment was limited to a basic power-hungry rig and a cheap off-the-rack multi-tester from your friendly neighborhood electronics store

What did we use to load the psu? It was not a pretty picture, but it got the job done.

The Seasonic M12-II Bronze 520 W is a surprisingly compact power supply with nearly the same dimensions as my TT Purepower RX 500w. It uses a 120 mm fan on its bottom and has an active PFC circuit.

It features a hybrid modular cabling system as opposed to full-modular systems used on most high-end modular psu’s. This only means that not all the cables are detachable. All cables have nylon protections, that come from inside the power supply housing. The modular cables are likewise sleeved and are of good length. All cables use 18 AWG wires, which is the minimum recommended.

Comparing the cables to the S12-II 520w, they have exactly the same connectors save for the molex to floppy adapter cable that was provided for good measure. The cables included are:

1. Main motherboard cable with a 20/24-pin connector (hardwired). 2. One cable with one EPS12V connector (hardwired).3. One cable with two ATX12V connectors that together form an EPS12V connector (hardwired).4. One cable with one six-pin video card power connector (modular).5. One cable with one six/eight-pin video card power connector (modular).6. One cable with three SATA power connectors (modular).7. One cable with three SATA power connectors (modular).8. One cable with three peripheral power connectors (modular).9. One cable with three peripheral power connectors (modular).10. One molex to two floppy power Y-adapter cable.

For the average Juan or Pedro who is making this unit his first true-rated psu purchase, this unit is a real feast for the eyes. The modular cables come in a nice sling pouch. There’s mounting screws and a shiny Seasonic sticker in the box. There’s a lot of information on the box to keep him grinning ear to ear. Although, I have seen more goodies-laden psu packaging, overall packaging is quite acceptable for an entry-level modular psu.

See that little piece of white paper in the box? The distro was kind enough to include information on how to get in touch with them for any concerns regarding their products as well as instructions on how to avail of their RMA services! Talk about great service!

Modular versus Non-Modular?

Looking at the picture above gives you an idea what a modular psu looks like with all of the cables plugged in. Some people prefer the cleaner look of a non-modular psu because the wires are all at one side. But it is undeniably nice to have the option of only attaching the cables that you need when you need them. This is really where the allure of having a modular psu comes in.

A look inside

The insides are practically the same with the S12-II 520w Bronze..

The main differences are the slightly longer housing and the modular cabling pcb that you can see at the top-left of the picture.

Want to know why Seasonic psu’s are quiet yet cool running? This guy is the reason! Coupled with a good fan-control program, these guys are hard to beat! If you get the chance to buy an ADDA fan from an aftermarket reseller, don’t let it slip by you!

I have seen many the underside of a generic psu. I have also seen many true-rated psu and I have to say that this is nice and clean! Where’s the like button?

And here is added proof that the S12-II 520w and the M12-II 520w use the same internals. If you have the time later, you can compare this from the picture in Gabriel Torres et. al.’s review that can be found in the internet.

See those yellow wires all soldered to the same spot on the pcb? This means that this psu is a single rail and not a multi-rail psu. What’s the difference? A multi-rail psu has overcurrent protection shunts that limit the amount of current that each rail can handle while a single rail psu has all the power going through a single line that may or may not have overcurrent protection.

Here’s what Gabriel Torres of Hardware Secrets has to say on this: “In summary, the single rail design has as advantage the power supply not shutting down if you are below the PSU maximum current capacity, however in a case of overload of a component due to a malfunction the PSU won't probably shut down as it will "think" that it is running inside the specs (it will shut down only if the component pulls more than the PSU total capacity -- i.e. the single rail capacity).

With multi-rail the advantage is that the PSU offers a better protection, as the PSU will shut down if a component pulls more than the value under the OCP is configured -- which is a smaller value than compared to single-rail designs (e.g. 18 A instead of 36 A with the same PSU built as a single-rail instead of a dual-rail).

But the disadvantage is that the OCP may shut down the PSU even if the components are working just fine, if you are using power-hungry components.

Which one is the best? This is an endless discussion that I don't have an opinion.“

Testing

Here’s a shot of the psu in the toasty confines of our hotbox.

The hotbox we used makes use of a 100w lamp that heats up the inside of the box to the precise temperature that we had previously set in the installed controller.

Testing Results

By the way, we first took the NO LOAD readings of the voltages from the psu after we brought it to life using the paperclip method. After that, we put it inside the hotbox then hooked it up to our test rig and fired up the system. We then ran Furmark on our test rig to force the system to run at full blast. At this point, we took the voltage readings that you see below.

Once we got to testing, we were both happy and sad. Happy to report that the psu easily handled everything and sad to note that we didn’t have enough to throw at the psu we had before us. Despite running furmark on our test rig, the psu’s voltages barely dropped.

We made sure that the psu was toasty inside the hotbox. The box’s temperature controller noted that the psu was taking in 40 degree air but the fan did not even reach full speed despite our best efforts. It was barely audible all throughout the test.

Looking at the data below, its easy to see that during the test, the 12v rail went down 0.4% from 12.27v to 12.22v. The 5v rail on the other hand went down 1.16% from 5.16v to 5.10v. The 3.3v rail did not even budge at all compared to the other two. In any case, these voltages are still well above the minimum required.

If there is anything we can conclude from the test, its clear that modern PC’s draw power primarily from the 12v rails to power most of the components and the video card then secondly from the 5v rail to power peripherals.

NO LOAD

WITH LOAD

+12V

12.27v

12.22v

+5V

5.16v

5.10v

+3.3V

3.38v

3.38

I really wished we could have done more with this review. I was sad to note that we were not even able to stress this psu at all despite our best efforts. In real-world situations, this would clearly mean that the average Juan would be hard-pressed to stress out a good true-rated 500w psu like this one. He would really need a lot of money and hardware just to give this unit a good workout.

And in real-world situations, this also means that a 500w psu is more than adequate for the average Juan or Pedro. I daresay that a GTX295 or a HD3870 X2 would be an even match for this psu. Now if only someone would be nice enough to lend one to us so we could do this test over.. Wink! Wink!

Conclusions

The Seasonic M12-II 520w Bronze is a wonderful psu. Despite our best efforts to stress it out, all we could manage was a 0.4% drop in the +12v rail and 1.16% in the 5v rail.

Although this unit is not exactly cheap and not without solid competitors in its market segment, it should still be noted that this unit presents an excellent value proposition because of its 5-year local distro warranty. Mind you that this is an entry-level modular psu that comes with a warranty that’s normally reserved for mid-to-high end units! Most of its competitors could only muster a 3-year warranty at most. Even then, they don’t offer a FULL local warranty for their units!

The only thing that would normally hold a person back from buying one of these units is the fact there is almost no difference in performance between the M12-II 520w Bronze and the S12-II 520w Bronze because of their near-identical internal makes. And the cost of going modular is about PhP550.00 for the same level of performance. But for the discerning buyer who knows what he wants, such a price difference is a trivial matter; he will buy it because it’s the best 500w modular psu for his money.

I have to admit that I am impressed with this unit. It was really hard to find fault with it in the first place. My only gripe is with the confusing dual-rail wattage rating on the label. Maybe Seasonic could address this matter somehow?

Before I close this review, let me present an excerpt from the Hardware Secrets review of the Seasonic S12-II 520w Bronze:

“Seasonic S12II Bronze 520 W is an excellent power supply. It passed with flying colors in our tests: efficiency between 82.4% and 86.5%, voltages closer to their nominal voltages than required (3% voltage regulation instead of the standard 5%) and ultra-low noise and ripple levels. Plus we could pull up to 588 W from it with efficiency still at 81.7%.”

If the above excerpt gave you a lust for more info regarding the performance of M12-II’s sibling, you might want to go and visit Hardware Secrets and look for their review of the Seasonic S12-II 520w Bronze. The main differences lie mainly in the fact that the M12-II is modular while the S12-II is not. Although I’m sure that the larger housing and the modular connector pcb will lead the M12-II Bronze to have a different airflow than its non-modular sibling, I’m inclined to think that the difference would be negligible.

About the reviewers..

bert21977 (left)

Sir Bert is an accomplished PC technician and is the proud owner of TPC Marikina’s Chop Shop. Its location is an absolute secret but if you pay us a visit at the TPC Marikina thread of Tipid PC, we might just let you in!

Godai_Yusaku (right)

Sir Ed is a PC enthusiast who likes to build computers for friends and do some computer maintenance whenever he has the time. He happens to be the resident troll of TPC’s PSU threads when he’s not hanging out in TPC Marikina.